The story of Thomas and his rivet mountain bike is incredible. It is impossible to say exactly where it all began. In his time as an "airfield kid", as Thomas calls the years in which he grew up as a three-year-old in the midst of the local small aircraft scene? When he was just five years old, he cannibalised an old tow truck for gliders. Or was the big bang the blue motorised plane that Thomas built himself in three years after completing his engineering degree and used to fly to Helgoland, among other places? But the tuning MTB project definitely began that morning in 2019, when he pedalled towards work on his old, rusty trekking bike after 25 years of cycling abstinence.
The idea: A lightweight mountain bike in perfection
Thomas is an optimist. In psychology, this is the name given to people who throw themselves into something in an almost spiritual way. All the way or not at all. And if they do, then as a 360-degree experience. That's how he created his aeroplane. And that's how he wanted to create the perfect customised mountain bike. While he was still pedalling away, the dream bike was coming together in his head, puzzle piece by puzzle piece.
"At home, I drew everything on a piece of paper, did a bit of maths and then got straight to work," recalls Thomas, who earns his living as an engineer in the automotive industry.
The question is not: How light do I build? But rather: How do I build light? - Thomas Lukasczyk, material expert and custom frame builder
Riveted connections as a solution for the custom mountain bike frame
Anyone who asks Thomas about his custom mountain bike is immediately sucked into the world of physics like air into a jet turbine. Terms such as stiffness stress, thermal distortion, yield strength, elongation at break and fatigue resistance swirl around his lips. If you're not sure-footed in higher physics, you're out straight away. However, even physics nerds realise this: The bike was not designed so extravagantly for the sake of attracting attention, but for technical sophistication.
"I don't think carbon or fibre composites are ideal for bicycle construction," explains Thomas. Finally, Thomas draws the bow to his special solution, but classic aluminium is also out of the question for him. For welding, you have to rely on alloys that don't have the best strength properties. The perfect alloys, in turn, would not be suitable for welding. The solution was to rivet the joints.
In principle, this is all aluminium foil. - Thomas Lukasczyk
Thomas ordered wafer-thin, high-strength sheets of 2024-T3 aircraft aluminium in the USA. And was immediately faced with the first problem. The material was relatively brittle. How would it be possible to bend it into the required profile shape without risking cracks or structural damage? With the help of a local metalworking shop and its CNC press brake, we finally succeeded. But only after several setbacks.
Thomas spent the following weeks in the cellar until late at night. Cutting metal sheets. Filing. Fitting. Setting rivet holes. Finally, the final, solemn ceremony: joining the individual segments together with aviation rivets. A meditative but demanding procedure.
"My master cell builder once said: After 1000 rivets, you'll know how to do it. After 10,000 rivets, you can do it," laughs Thomas.
Days later, the extravagant custom mountain bike was fully assembled. The weight that the scales showed made Thomas happy: 10.5 kilos. More importantly, however, the bike proved to be extremely agile and hungry for kilometres. Thomas rode more and more often. He became fitter. He squeezed 20,000 kilometres and 500,000 metres of altitude into his legs. He felt there was still room for improvement. He decided to build a second version of the riveted tuning bike. With even more attention to detail. Even more radical. Even lighter. Project Maximum.
"If you're two seconds off your best time after a 30-minute Strava Uphill segment, you can easily work out how many grams were too many," says Thomas. The magic of speed and lactate had completely taken hold of him. He hadn't ridden a bike for 25 years. Now he even knew Strava.
Again he ordered sheet metal in the USA. Again he cut and filed and riveted. This time he celebrated it so much that he even became a zombie.
While he was setting the rivets, which resemble sharp nails, Thomas had the idea of recreating the film poster for the 80s splatter classic "Hellracer - The Gateway to Hell". The poster shows zombie Pinhead with terrifying nails stuck in his skull. Thomas shaved his hair, put on cold white make-up and hung the provisionally stapled frame on the snow chains of the family car. Mrs Ulrike, a photographer, pressed the shutter release. "Fast racer", was Thomas' headline when he posted the picture on a forum.
Custom mountain bike number 2: It has to be even lighter
Thomas had set himself a target weight of 1400 grams for the new version of the riveted MTB frame. A good value for a hardtail frame, but a far cry from the dream values of the carbon models from large premium manufacturers, which weigh half a kilo less. The bike should weigh less than 8.0 kilos ready to ride. Thomas realised that it would depend on the equipment. For weeks, he scoured the internet for potential parts, entered the parts into Excel spreadsheets, calculated, tinkered and slowly approached the optimum ratio of weight and stability.
When the frame was finished in mid-2022, the next shoot was due. Another homage to a classic film. This time, Thomas wanted to pay homage to King Arthur with the frame. Wearing chain mail bought online and a Burger King crown, he recreated the Excalibur scene on a stone from the famous Menhir site in Darmstadt. Like King Arthur the sacred sword, costume king Thomas pulled the frame out of the stone. His wife, who also pressed the shutter release for this motif, later added a dramatic flash to the picture.
"The chain mail was ten times heavier than the frame," laughs Thomas.
The frame was ready for assembly. But the question of the wheels was still taking up Thomas' time and nerves. The beasts seemed to be challenging him. No wonder. They shouldn't weigh more than 1000 grams. But they had to be built with the indestructible hubs from Chris King. Thomas entered every conceivable combination of King hubs, rims, spokes and nipples into an Excel spreadsheet, but the total that the numbers spit out was higher every time.
It was exasperating. He had managed to build an aeroplane and fly it to Heligoland. And now mountain bike wheels, of all things, were showing him the limits of what was possible. He had already decided in favour of 27.5-inch wheels rather than 29-inch rims. Softened by the endless search for even lighter nipples and rims and the constant back and forth calculations, Thomas finally decided on a compromise. The hubs from the Italian manufacturer Carbon Ti were perhaps not quite as iconic as the of the US-American parts god Chris King. But they were light. And the aggressively hoarse sound of the freewheel had a similarly stimulating effect on the happiness hormones.
The custom mountain bike was finally finished in the summer of 2022. Fidgety with excitement, Thomas stared at the display of the digital scales. 7980 grams! An insane figure.
Thomas is satisfied. But he already has a third version in mind. If he were to build the bottom bracket housing and the head tube from aluminium instead of steel, then at least a small weight saving would be possible. This is still only a tender thought. But anyone who knows Thomas knows that it's highly unlikely to stay that way.
The riveted custom mountain bike in detail
- Frame: Self-build, aluminium/steel
- Fork: Rockshox SID Worldcup
- Brakes: Formula R1 Racing
- Circuit: Sram XX1 AXS
- Crank handle: Sram XX1 with 40 chainring (Alugear)
- Impellers: Carbon rims (no name) 27.5 inch, carbon Ti hubs
- Tyres: Schwalbe Thunder Burt 27.5 x 2.25 inch
- Handlebar/stem: Extralite
- Saddle: Becker Carbon
- Weight: 7980 gram
